Creatherm Radiant Floor Panels, made of expanded polystyrene, interlock so as to provide a pre-molded channel system that accommodates PEX thermal tubing, which circulates water from a boiler, water heater, etc. The panels are designed to be easy to install, ensure proper tubing alignment, and eliminate 'hot spots' under a variety of overlaid flooring materials, including concrete, wood, tile, gravel, and soil.